The economy of the United States, if not of the world, depends to a great extent on fleets of large trucks for the distribution of goods, such as foods, consumer products, durable goods, and even industrial equipment. There are many manufacturers of such trucks, which concern primarily, but are not limited to, class 7 or class 8 over-the-road trucks. Once these trucks are manufactured, they require shipment or transportation either to the carrier or other company for whom the truck was made, or to a dealer who sells or leases these trucks. The most obvious method to transport these trucks is by driving them directly to their destination. This method has disadvantages, at least because each truck requires a driver, who must be paid for his or her services and for whom return transportation must be arranged.
In order to overcome the necessity of a driver for delivering each truck, a variety of techniques have been devised to use a first truck that will carry or tow one or more additional trucks to the desired destination. One example is shown in U.S. Pat. No. 4,555,214. This patent discloses a tow bar that attaches to the fifth wheel of both the towing vehicle and the towed vehicle. The towed vehicle is towed in a rear-ward fashion behind the front vehicle. Using this technique, the towed vehicle is exposed to the full force of the air that is encountered during the tow. Any aerodynamic surfaces of the towed vehicle will be subjected to reverse stresses, i.e., the wind will impose loads on the truck at 180° from the direction expected during the design of the truck. Thus, the roof cap, side fairings, and any additional fairings, such as side and chassis fairings, should be braced or buttressed for the trip. This adds additional cost to the delivery of the truck. In addition, it is not clear that, even using both fifth wheels, the towed truck will have sufficient freedom of movement to be able to rotate slightly during turns.
Another technique is disclosed in U.S. Pat. No. 4,867,468. This patent discloses a decking bar that mounts to the truck chassis in front of and above the front axle of the towed vehicle. The decking bar has a relatively uniform cross section with differently-shaped end portions and is also relatively short. Using this technique, the towed truck is lifted vertically and is not drawn close in a horizontal direction. In order to minimize the vertical lift, the decking bar is mounted above the front axle of the towed truck, which is then suspended by mounting the decking bar to the chassis of the towed truck.
Another technique is disclosed in U.S. Pat. No. 5,873,593. This patent discloses a piggyback truck transport system. Using this system, a first towing truck mounts a second towed truck on its rear portion. The towed truck is lifted a substantial distance in a vertical direction, putting a stress on the truck and also putting the combination load at risk for violating a vertical height limit. The towed truck is lifted a substantial distance because its front wheels rest on the rear of the towing truck, thus elevating the towed truck a considerable distance. This height may limit the route which is taken in delivering the trucks. The height may be lessened by removing the front tires of the towed vehicles, which also adds to the delivery expense.
Another technique is disclosed in U.S. Pat. No. 6,109,642, for a self-lubricated king pin and saddle assembly. This patent discloses a unique structure and method for lubricating a king pin during towing. The king pin continuously receives lubrication from a series of channels and reservoirs that are periodically refilled. While useful, this apparatus and technique does not solve any specifically aerodynamic problems.
Trucks may also be transported with equipment and a method disclosed in U.S. Pat. No. 6,120,051. This patent discloses a method in which a first truck tows a second, rear-facing truck, using a special beam assembly. In this method, a boom saddle is used in conjunction with the fifth wheel of the towing truck and the fifth wheel or a support mount of the towed vehicle. The special provisions of the boom saddle allow for lateral and vertical movement of the beam assembly. While this method works well, it continues to have the disadvantage of towing a vehicle that faces rear-ward. Thus, the structure of the towed vehicle must be braced or buttressed during towing, adding to the cost of the tow. In addition, the extra wind resistance of the open rear portion of the truck detracts significantly from fuel economy during a long tow, such as from a manufacturer to a customer or dealer.
The invention provides better equipment and a better method for towing trucks. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.